This application pertains to the art of detecting and reporting devices and more particularly to a self-contained device for detecting and reporting some predetermined condition in a rotating body.
The invention is particularly applicable to detecting over and/or under inflated conditions in pneumatic vehicle tires and will be described with particular reference thereto. However, it should be appreciated by those skilled in the art that the invention has far broader applications and may be utilized in many other environments where it is desired to detect and report or indicate some predetermined condition in any rotating body.
Both over and under inflated conditions for pneumatic tires is a cause for excessive tire wear resulting in premature tire failure. Moreover, such under and/or over inflated tire conditions can have an adverse affect on the efficiency of operation of the vehicle as to both vehicle performance or handling as well as vehicle gas mileage. Since such conditions and results have been well known for quite some time, there have been many attempts to develop and provide means for automatically detecting and reporting under and/or over inflation. Recently, development efforts for a practical and inexpensive device have become more concentrated due to the rise in fuel and tire costs as well as vehicle operation costs in general.
While there have been quite a number of prior devices developed and utilized for detecting tire inflation conditions, all of these prior devices have had structural or operational shortcomings rendering them undesirable or impractical for widespread use. While the specific prior devices have been many and varied, most have required special wiring and the like extending from the wheel assemblies to the vehicle chassis and then through the vehicle body to the instrument panel. Such wiring adds undesired costs to the system and, moreover, is extremely difficult and time consuming to install. Such installation time is particularly important when considered on the basis of installing the devices during original vehicle assembly for making them a part of the original vehicle equipment. Further, the necessary special wiring and associated equipment extending between the wheels and chassis are such that they are susceptible to damage or breakage from road materials, weathering and the like encountered during normal vehicle use.
There have also been some prior attempts at developing self-contained detector apparatus in an effort to eliminate the necessity for wiring and the like between the wheels and chassis, but these prior attempts still have not proved totally successful and effective. Specifically, these prior self-contained units have utilized small signal emitters such as a radio transmitter disposed at each wheel. These emitters transmit a signal such as a radio signal in response to some predetermined inflation condition detected in the tire by sensing means. The signal is then received in the vehicle and utilized to energize a warning indicator or light to advise the vehicle operator that an over or under inflated tire condition is present.
While generally overcoming the wiring problems, the means employed for powering the emitters has thus far proved to be unacceptable for practical widespread vehicle application. Typically, these power means have comprised small batteries associated with each wheel or other, rather exotic and complex circuitry. Batteries must, of course, be periodically replaced as their useful life expires and it is impossible to precisely determine the extent of this useful life as it will vary between individual batteries and between individual manufacturers thereof. Moreover, it has been generally found that many owners are extremely lax with regard to all periodic vehicle maintenance including even such basic items as oil and lubrication. As a result, owners would also simply forget or not take the time to properly check, maintain and replace these small batteries. As a result, this type of self-contained detector would often be inoperative and, therefore, of no practical value or use. The other, rather exotic and complex circuitry had the disadvantage of being costly and subject to damage or destruction during normal vehicle use.
Still another disadvantage with prior tire inflation detecting and reporting devices or systems was that their effectiveness depended to a great degree on the rotational speed of the wheel itself. This fact was due to their very design and construction such that the devices were really only effective at elevated vehicle speeds and did not properly operate at normal city driving speeds. Moreover, many of the prior devices were only uni-directional and thus were only operative in one direction of rotation. Accordingly, such devices were limited to mounting on one side or the other of a vehicle.
A still further problem with the prior devices of this general type has been in the necessity for providing operative communication between stationary and rotating components. Because the devices are generally electrically operated, prior devices found it necessary to include slip ring structures to operably interconnect the various components and such structures were found to be susceptible to damage or the like necessitating repair and/or replacement.
The present invention contemplates new and improved apparatus and method which overcomes all of the above referred to problems and others and provides apparatus and method for indicating the condition of a rotating body which are simple in design, economical to manufacture and install, which require a minimum of component parts moving relative to each other during operation, which are self-contained and do not require outside or replaceable energy sources and which are readily adapted to use for any number of detecting functions in a number of environments having an associated rotating body.